MELBOURNE, May 14 (Reuters) - The coal price slump that brought Australian tycoon Nathan Tinkler down last year has also sown the seeds for his comeback, with the former electrician snapping up a closed coal mine from Peabody Energy for next to nothing.

Tinkler's Singapore-based firm Bentley Resources agreed to buy the Wilkie Creek mine from Peabody for $70 million in cash, plus the assumption of $60 million in various obligations and liabilities, in a deal announced on Tuesday.

The sale came as a surprise to bankers and analysts, who knew that Peabody had wanted well over $500 million for the mine when it was put on the block two years ago.

After failing to attract a buyer, Peabody closed Wilkie Creek in December 2013, blaming weak coal prices, high costs and the impact of Australia's carbon tax, which the current government aims to repeal.

A Peabody spokesman was not immediately available for comment after hours in the United States.

Just a year ago Tinkler was forced to give up his stake in Whitehaven Coal Ltd, the biggest source of his wealth, to pay off creditors, and sell his prized horse farm and Aston Metals business.

"I was shocked Nathan's back. It's extraordinary. But he's a businessman. He's made plenty of money from making calls that other people haven't in the past," said Lawrence Grech, senior resources analyst at broker Octa Phillip.

Tinkler, now 38, was a pit electrician when he made his first big bet on coal, buying an unloved project for A$15 million in 2006. Within two years he had minted a profit of more than A$625 million on the deal and went on to buy another project, Maules Creek.

Riding a China-driven coal boom, his fortunes peaked in 2012, with the $5 billion merger of his Aston Resources and Boardwalk Resources with Whitehaven Coal.

"He's not just lucky. He worked really hard. But he pushed the envelope in terms of risk," said Andrew Harrington, who runs the coal consultancy Indexys.

But it all started to unravel in the second half of 2012 as coal prices started to slide, hitting Tinkler's mining, sports and horse-racing empire, and he ended up moving his family to Singapore from Australia's coal hub of Newcastle.

Australian thermal coal export prices are now at their lowest levels in more than four years, with the Newcastle weekly spot index holding around $73 a tonne for the past couple of months.

The Wilkie Creek is an aging, thermal coal mine, in stark contrast to the undeveloped Middlemount and Maules Creek projects on which he made his billions. Analysts and bankers questioned how profitable this new deal will be for Tinkler.

"They're chalk and cheese," said one banker, who declined to be named, as he was not involved in the Wilkie Creek deal.

Tinkler has lined up debt from Leucadia Corp, according to media reports, the same investors who made millions backing iron ore magnate Andrew Forrest's Fortescue Metals Group.

Based on how Tinkler funded his previous deals, analysts say he is unlikely to have put much of his own money down on the deal, and would probably face hefty interest costs on any loan from Leucadia.

Tinkler's spokesman said he did not know how much debt Leucadia had provided for the Wilkie Creek acquisition. Tinkler, who was on his way to Sydney to appear at a state hearing into political corruption, was not immediately available for comment.

Analysts said the structure of the deal will be key. Tinkler could come out ahead if recent moves by big Chinese investors on Australian resources companies are any indication of north Asian appetite for Australia's iron ore, coal and copper, they said.

"Hopefully the funding arrangements will have the longevity needed to play out his business strategy in the face of challenging commodity markets," Grech said. (Reporting by Sonali Paul; Editing by Tom Hogue)